The aim of the present article was to study the question of do special exercises for the formation of students-psychologists skills determine the causes of deviant behavior of adolescents, based on the provisions of the causal approach in psycho-diagnostics A. F. Anufrieva, the principle of objectivity. The study involved 30 future psychologists. After performing the exercises in the course "Psychodiagnostics" the students solved the task, which simulates diagnostic work of the psychologist with decriminalised teenager with deviant behavior. Students were asked to solve a problem in professional discourse – to put forward hypotheses about the causes of deviant behavior in everyday life is to point out the culprits of the situation. Additionally, students assessed their similarity with the hero of the diagnostic event. The results show that students who have managed to build up diagnostic skills to identify psychological causes of deviant behavior, both professionally and in everyday discourse grappled with the task model, regardless of the number of subjective similarities with her character. Students who have not sufficiently developed diagnostic skills, to avoid bias failed.